Thread: Struct pointer initialization

Hello everyone,
I wrote a piece of code here, which actually works, but I was told to initialize the data structure that holds the data to be filtered and I dont really understand how to do this.
As you can see

double* Values; // holds the data to be filtered

The pointer Values will be used to create a dynamic array, but first I was told to initialize it . So, how do I initialize it?
I have a function

void EnterData(TheData& DataIn)
{
// initialize the data structure that holds the data to be filtered, including getting
// the number of data values from the user

cout << "Please enter the number of data values to be filtered:" << endl;
cin >> DataIn.Length;
cout << endl;

So, I was trying to write something like DataIn.Values = NULL to initialize the structure where data will be held, but it doesnt really work.
Thank you for any help.
Here is a full code.

Code:

#include <iostream>
using namespace std;

struct TheData 
{
  double* Values;  // holds the data to be filtered
  unsigned long Length;  // number of data values
  bool Valid;   // true if the data values have been Valid by the user
};

void EnterData(TheData&);


int main()
{
	int a;
	TheData OriginalData = {0,0,false};
	EnterData(OriginalData);
	cout << endl;
	//cout << OriginalData.Length;
	cin >> a;
	delete [] OriginalData.Values;
	
}
// Allow the user to enter the data to be filtered
// Arguments:
//   (1) the structure containing the input data
// Returns: nothing
// 
void EnterData(TheData& DataIn)
{  
	// initialize the data structure that holds the data to be filtered, including getting
	// the number of data values from the user

	cout << "Please enter the number of data values to be filtered:" << endl;
	cin >> DataIn.Length;
	cout << endl;

	// allocate memory to the data
	DataIn.Values = new(double[DataIn.Length]);

	// obtain all of the data values
	cout << "Please enter the data values to be filtered:" << endl;
	for (unsigned int i=0; i<DataIn.Length; i++)
		{
			cout << "Please enter value #" << i+1 << ": ";
			cin >> DataIn.Values[i];
		}
	DataIn.Valid = true;
	cout << "All the values were saved successfully.";
}

Yes, but the task tells to initialize Values again in the function. I dont really understand why and how as well as what for. but this is the task given. I need to do it in the place, where I colored with green So, is there any way? because if I say, create another pointer like
double **testpointer and write
testpointer = &DataIn.Values to check the address of DataIn.Values, then testpointer will point to some memory location, where DataIn.Values is being kept and this address appears to be not zero... How do I make this pointer DataIn.Values to point nowhere, until I allocate memory for DataIn.Values using new?

Thank you for your help. I guess I will leave just DataIn.Values = NULL, because I can't read my lectruer's mind lol